(1) Field of the Invention:
The present invention relates to a photosensitive material for electrophotography. More specifically, the present invention relates to a photosensitive material for electrophotography, which is excellent in the ozone resistance and the moisture resistance.
(2) Description of the Prior Art:
As one kind of a photosensitive plate for electrophotography, there has been widely used a photosensitive plate comprising a layer of a composition comprising a dispersion of a photoconductor in a binder resin, which is formed on a conductive substrate. When this photosensitive plate is used for electrophotography, the photosensitive plate is charged by corona discharge of a certain polarity and is then subjected to imagewise light exposure to form an electrostatic image, the electrostatic image is developed with a toner, the toner image is transferred on a copy sheet from the photosensitive plate, and the surface of the photosensitive plate is cleaned. This reproduction cycle is repeated.
Among photoconductive pigments used for such photosensitive plates, cadmium sulfide is especially excellent in the sensitivity. However, when a photosensitive plate comprising cadmium sulfide as the photoconductor is used for reproduction repeatedly for a long time under a high-humidity condition, the image density is drastically reduced.
Cadmium sulfide is an n-type photoconductor and hence, it is subjected to corona discharge of a negative polarity. Accordingly, the photosensitive layer is always attacked by ozone and is rendered sensitive to the humidity. It is construed that the initial charge potential is reduced for this reason.